The trials and tribulations of having an eco house built - and then living in it!

Thursday, 11 July 2013

Living In Harmony with My House

It is very odd to live in a house with a personality (GoT and Harry Potter notwithstanding) but that's what we've got here. After 15 months of living with each other I finally realised the house was on our side when it trapped two strangers in the porch for nearly an hour and wouldn't let them out (not so much a case of beware of the dog, but beware of the house!). Since then I've been applying intuition and science to the process of working out how the house likes to be treated and, thanks to engineering friends and email correspondents, we're now getting along fine.

As ever we've had a regular supply of visitors to look at the technology, tweak things and mutter dark remarks about other visitors who have been out to look at the technology and tweak things. This used to get me down but since the house started to repel boarders I've found it more amusing and the more I understand the house, the better I become at asking the right questions and minimising the number of tweaking visitors - it's like a domesticated version of homeostasis really.

We are still waiting for the rainwater harvester to deliver as the loos on the top floor cannot refill when flushed, unless they are supplied by mains water. About a month ago several gentlemen from the company that provided the harvester spent an afternoon in the house with buckets, lifted up the manhole covers in the garden and shook their heads at the folly of earlier gentlemen. It turns out that the water supply to the harvester should come into the house via a flexible pipe rather than a normal pipe network and it is the joints in the current arrangement that lead to the impressive water hammer whenever we switch from mains water to the harvester supply. On the plus side, whatever they did during their visit, stopped the sound of running water that we had been experiencing 24/7 since January and apparently once the solid pipe supply is replaced all will be well. They assure me that this work will not necessitate any digging up of my garden which is good news because the garden has undergone a transformation thanks to considerable effort by yours truly ...

... and if my
artistic endeavours are damaged I will be forced to loose the house on
them

Solar Gain

Last summer the top floor exceeded temperatures of 26 degrees on sunny days in summer due to a combination of the warm air in the house rising and the lack of shading which then allowed sunlight through the triple-glazed roof windows. We expected the south-facing rooms to heat up but we were surprised that between May and July the two windows on the north corridor also had sun pouring through them. Last month, just in the nick of time for the heatwave, we had canvas external blinds fitted and that has reduced the temperatures on the top floor by at least 3 degrees. The blinds only reduce the light in the rooms a little, as if it were a cloudy day, but the heat reduction is phenomenal.

Air Flow

In my last blog
post I was puzzled by the fact that in winter the ground floor rooms
were cold, despite both the amount of extra heat we were pumping into
the building and the claims that this house would be a constant
temperature throughout the year. During the snows of February/March,
following a discussion during a school visit, my suspicions about the
structure of the house were confirmed. Essentially our stairwell acts
like a chimney and draws all the heat of the building up to the top of
the house. The ventilation system pushes extremely warm air into the
rooms through the little Saturn openings and this is supposed to obey the coanda effect
and waft across the room gradually cooling and sinking as it goes and
bathing everyone on the far side of the room in its warmth.
Unfortunately, on the ground floor, the force of the draw through the 'chimney' of the a
three-storey stairwell is stronger, so the warm air gets about half way
across the room before being sucked out under the door and off to the
top floor. This is great during a summer heatwave but by the end of the winter I was putting a
plug-in radiator on the opposite side of the room to the door and
benefitting from that warm air going over me on its journey roofwards.

Ventilation

The Mechanical Ventilation. Heat Recovery (MVHR) system is what stops us running out of air in our airtight house and as well as supplying constant fresh air it assumes that if the house is cold you want to warm this air up and if the house is too hot you want to cool it. Thus the air coming into the house might, or might not, be warmed by reclaiming the heat energy from the outgoing air. Sounds simple unless you get given the manual in German and instructions whilst you're unpacking crates a couple of days after moving. Anyway, after many a happy hour trying to make sense of this (thanks to Sue and John for the engineering help!) and following advice from Green Building Store, when I had my notebook ready, I now understand how this works. Depending on the parameters I set on the touch panel in my hallway I can tell the MVHR to reclaim the heat or not reclaim the heat and decide whether I want to draw in air at the same temperature as the outside air, or air that has been pre-cooled or warmed (depending on the season) by being passed under the ground in the rehau pipes. I did actually know the theory of all this before now but I couldn't find out how to do it and my new knowledge plus the external top floor blinds means the house is much more comfortable on a sunny day. If I need extra cooling I just have to calculate whether the external temperature is higher or lower than the internal and open the windows on the relevant floor if I want to 'purge the heat'. Once you get the hang of it it's all very simple and logical but there's nothing passive about all this is there? Although, of course, the word passive does come from the Latin verb patior which my dictionary suggests could be translated as 'to put up with something'.

Biodiversity

When we first moved in I was rather sceptical about the addition of a hogitat to attract hedgehogs but our household has actually been supplemented by a hedgehog. Admittedly said hog isn't living in his/her recommended abode but in a corner of the garden I've left wild but it is the first hedgehog I've seen since we moved to this neck of the woods.

Similarly the new pond was alive with tadpoles and water boatmen this year who all found their way to it unaided.

We have also done our bit for bees by having lots of nectar-rich plants and planting grass seed that has turned out to be predominantly clover. This will be all well and good for enriching the soil by fixing nitrogen but the bees adore it so grass cutting now includes shooing bees and froglets out of the way of the mower. It makes mowing rather complicated but as this is the only planet we've got I figure it's worth looking after!